Synthesis, characterization and antimicrobial activity of new Cu (II), Co (II) AND Sn (II) complexes with the sodium Hydrotris(2-Mercaptothiazolyl)borate ligand

Abstract

The emergence of antibiotic resistance among microbial pathogens is a serious public health problem, resulting in a constant need of discovering new antibiotics. For this purpose, we synthetized and determined the antimicrobial activity of copper (Cu), cobalt (Co), and tin (Sn) complexes coordinated with scorpionate ligand in a tridentate mode against microorganisms of clinical importance. New complexes with the sodium hydrotris(2-mercaptothiazolyl)borate ligand were characterized by physicochemical and spectroscopic techniques (UV-vis, IR, 1H and 13C NMR). Moreover, their antimicrobial activity was evaluated using microdilution broth method. Cytotoxicity was determined in Vero cells and the selectivity index (SI) was calculated. The coordination with metals increased the ligand antimicrobial activity, which showed no activity when evaluated alone (MIC>1,080 µM). Cu-complex (1) had activity against Candida albicans and C. krusei, with MICs of 130 and 66 µM, respectively. The compounds had low toxicity on Vero cells and chemo-informatics assays corroborated a low systemic toxic effect. The SI revealed that the compound 1 was 16 times more selective for C. krusei and 8 times more selective for C. albicans in relation to Vero cells. The Cu-complex stands out as a potential prototype for the development of new antifungal agents.